Drawing instrument.



E. T. CHILDS. DRAWING INSTRUMENT.

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Patented Apr. 16,1912. v

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EARL CHILDS, 0F CORAOPOLIS, PENNSYLVANIA.

DRAWING INSTRUMENT.

Specication of Letters Patent.

Patented Apr. 16, 1912.

Application filed October 10, 1911. Serial No. 653,763.

. To all whom it may concern:

Be itknown that I, EARL T. CHrLDs, -a citizen of the' United States, residing at VCoraopolis, in the county of Allegheny and thereon and adapted to be adjusted to or from a fixed point or line from which the measurements are to be taken in laying out the work, by means of which combination .drawing .the extreme end of the draftsmanswork may be simplified and expedited, giving him the use of several tools or instruments combined into one, which usually are'separate and not always within reach, and the invention consists in the novel arrangement and combination of parts as will be fully described hereinafter, reference being had to theaccompanying drawings, forming part hereof, lin which- Figure 1 is ,a plan'view of my improved instruments, the same being constructed and arranged in accordance with my invention. Fig. elevation of the same. Fig. 3 is a sectional elevation on the line-m. w. Fig. i is a similar view on the line y'. y.

To construct a T-square in accordance with my invention, I form from wood or other suitable material a double head 1. and 5. the one part fixed at right angles to a thin blade 7 and the other to a 'fixed pivot 8, whereby said head may be made rigid with thev blade at any angle desired. rIhe fixed head 5 is under cut (6)- to permit the blade to move about the pivotal point 8, and may be clamped at any point within a specific limit, by .a clamp screw -which comprises a threaded bolt 12,.pro]ect1ng through a circular slot 3, formed 1n the movable head 1, and a large -thumb nut 13. Atthe blade 7 is a pointer 7 which is in close contact with a spaced 2 is a central sectional/ arc 2, which will indicate to the operator the exact number of degrees at which the blade T is set, thereby forming a protrae-tor.

The working edges of the square consists i of a rectangular frame 20, slidably mount ed upon the blade 7.. in such manner that. the said frame may be moved along the length of the blade 7. These working edges if() are suitably graduated, indicating inches and fractions thereof, and are connected the one with the'other by thin metal strips 21 and 21 operating within reduced parts 22 and Q2 formed transversely with the bladey 7. Th'e outer extremities of the working edges are attached, the one with the other. by a thin metallic strip 24. passing through av mortise or slot 23 formed across the blade T.

To afford a means of moving thek graduated working edges 20. a microscopic distance or to any fractional part of an inch to the desired point and maintaining the same thereat the said working frame 2O is attached to a threaded bnr 15. placed in a slot 14 formed in the blade 7, the threaded portion of the bar being connected with a vertically arranged thumb nut 18` the-said nut being mounted and held in its normal position by bearings 17 supported by a bridge-piece 16. said bridge being arranged over the slot let and attached to or integral with t-he movable blade 7.

The pivot which attaches the blade to the movable head 1. comprises an enlarged head 2) a large shank 9 through which is passed the adjusting screw 15. and reduced integral threaded shank 1() to which a thumb nut 11 is attached. .By this construction of the pivot for the blade 7 it is 8 (see Fig.

possible to operate the adjustingr screw direct-ly through the longitudinal center of the blade. which will prevent binding of the working frame Q0. and at the same time with the aid of the clamp screw 13, rigidly attach the blade to the movable head 1 at two widely separated points, which is obviously an advantage, making. the blade 7 as firm with said head as if it were permanently secured.

n operation, both of the working edges 20 are graduated, and the square turned up side down using either the movable or fixed head. The blade 7 may be turned in either direction to the limit of the arc 3, and fixed ment may be accomplished regardless of the at any angle Wit-h the movable head 1 by the thumb screws 8 and 13, asl-Will be best seen by dotted lines, at Fig. 1 of the drawings.

" In .order to shift the Working edges 20 in either direction along the length of the blade 7, and maint/ain the same in adjusted position it is only necessary'to operate the thumb nut 18 in the properdirection. This moveposition of the blade 7 With reference to the movable head 1.

The practical -operator-\vill recognize the useful combinations of the above'described Vtool or implement, which includes an adjustable scale, a protraetor,

an adjustable head for angular Work and an ordinary T i square. s

.Square having a blade and `Working edges adapted to i lng the same in adjusted position.

2. A combination tool comprising a T l square having a blade and fixed head, 'Working edges along the length of said blade and an adjusting screw for'moving said worklng edges relative to the blade length.

3. A 'combination tool comprising a T square having a lblade and fixed head, Work# ing edges along the length of said blade, an adjust-in screw for moving said edges in either direction relative to the blade length, a movable head xed to said blade by a pivot whereby said head may be turned at various angles with said blade and Working edges.v j v 11. A combination tool comprising a T square having' a blade and fixed head, graduated Working edges along the length of said blade, means for moving said edges along the length of said blade, apivot'ed head connected to said blade,a protractor or spaced arc formed on said movable head and a pointer in line With the longitudinal center ofthe blade.

In testimony whereof, I have hereunto signed my name in the presence of two subscribing Witnesses. v v -i EARL T. CHILDS. In the presence of CLARENCE A. WILLIAMS, E. J. R. BLAKELY. 

